Spark plug



G. L. THOMPSON Feb. 28;

SPARK PLUG Filed Nov. 26. 1986 NVETOF? Gus L.. o Psov. 2

Patented Feb. 28, 1928.

GUs LEE TI-IOMPSN, OF' TFALO, NEW YORK.

.SPARK iPLUG.

Applicato n filed November 2 6, 1926. Serial No. 150,962.

My invention relates to improvements in spark plugs and the object of the inventoii ;is to construct a plug which will'produ ce a 'double spark under all functioning condi-` tions, and a. further object of the invention is to so mount the points inrelation to each` vstructed and arranged all as hereinafter more particularly described and illustrated in the accompanying drawing, in which:

Fig. l is a vertical cross scctional View through my plug.

Fig. 2 is a side elevational View of the plug, and, v

Fig. 3 is an invertedplan View thereof. Like characters of reference indicate .corresponding parts in the different views The plug shell l conforms in appearance to the standard type, being furnished at its upper end with a heXagonal spanner receiving member 2 and at its lower end with an exteriorally threaded portion 3 which is of course adapted to be' threaded into the engine cylinder. Interiorally of theplug shell 1 and intermediately of its length I orm a boss 4 of reduced diameter. which is adapted to support the porcelain insulator 5 which is 'inserted into the shell. The insulator is of cylindrical formation having an cnlarged ring 6 formed thereon internediately of its length, the lower end of such ring being adapted to be seated within an enlarged portion 7 in the upper end of theboss 4, so that the outer edge of the lower face of the ring rests upon the shoulder 8 tormed be tween the inner face of the boss 4 and enof such sleeve being enlarged and adapted to surround the upper end of the ring' 6, the upper edge of such ring being chamfered as is also the shoulder formed by the enlarged lower end 10 of the sleeve 9. The

upper end of such sleeve is of course fur'- nishedwith a hexagonal spanner receiving` portion' 11. v e

12 and 13 are a pair of metal rods einbedded within .the porcelain 5, the rod 12 projeeting through the upper end thereof and being suitably threaded to constitutethe usual cable receiving'binding post, a thuinb nut 14 being threaded 'thereon', the lower end of such rod pro ect1n g below the lower face of the porcelain 5, and adapted to constitute one of the plug points 15. For preventing any possibility of `the 'rod 13 rotatng with'- in the porcelain 5" and thus allowing the member 16 to move out of its aligned position I provide aturned-over upper end 19 ,upon the rod and also a bend 20 intermediately of its length which willpositivel y pre vent any rotative movement' as the porcelain is', molded around the rod.

Upon the lower end of the rod ,13, I fur nish a circular metal plate 21, such'plate being of slightly less diameter than the interior diameter .of the boss 4- to permit it passing therethrough and furnishedwith an orifice '22 into which the lower end of the i point 15 projects, the distances between the 'point 15 and the periphery of the orifice 22 .and the periphery of the plate 21 and the point 17 which extends downwardly from the inner face 18 of the spark plug shell being such that spark gaps of correct width are formed. r

The operation of my plug under working conditions is as `follows:

When the electrical .current passes from the e ap into the rod 12, it .jumps from the point 15 across the gap constituted between such pointand the periphery of the orifice 22 in the plate 21 and passes from thence across the plate and junps to gap constituted point 17, froni` where it follows the usual path into the engine block. It' will' be appreciated that the spark at all times, when 'functioning must jump both gaps as the plate 21 constitutes its only passage thru to the engine block. Should one of the gaps become .bridged -with carbon, the current* between the periphery of the plate and the i lOO interior of the block shell, and as it is also of slightly less diameter than the interior diameter of the boss& in the shell, the porcelain 5 can be readily removed for cleaning purposes without damag e to either the plate or points.

conditions and which will produce a single spari( even though one` of the ga-ps become completely bridged with carbon.

What I claim as my nvention is:

A spark plug for internal combustion engines comprisng a main body portion pro Vided with a bore open at its lower end, a pair of electrodes embedded within the body 1,eeo,635

of insulating material positioned within the main body portion, one of said electrodes communicatng with the spark plug cable, the other electrode being insulated within the 'body of insu'lating materiaha third elec trode depending from the inner wall ofthe positioned upon 'the lower end of the in sulated electrode' and havngan orifice therein 'into which the electrode communicating e 'with the'cable projects, the side of the orifice Gus LEE THOMPSON.

bore of the main body portion, and a plate 

